Crystal devices which are ground to dimensions to cause a vibration at a specific frequency when energy is supplied are employed in a large number of electrical applications. For example, such devices are used to establish the transmitting frequency of fixed frequency transmitters or to provide a stable reference frequency for frequency synthesizers. Such crystal devices often include two or more electrical connecting pins which are adapted to be soldered into a printed circuit board or plugged into a corresponding socket. These crystal devices generally employ a metal cannister providing environmental protection to the crystal blank. Means internal to the metal cannister are provided for effecting support of the crystal blank and connection to the electrical connecting pins.
The frequency determining characteristic of a crystal blank is its resonant frequency which depends primarily upon the thickness and the dimension perpendicular to the thickness of the crystal blank. Such crystal blanks are often circular and on the order of 0.2 inches in diameter and between approximately 0.002 and 0.006 inches thick. It will be appreciated that such crystal blanks being very thin and crystalline are therefore very brittle and delicate. The necessity of protecting such crystal blanks during the manufacture and use of such devices is obvious.
Currently, such devices are manufactured by manually mounting an appropriately dimensionsed crystal blank in a support with conductive epoxy. The blank is in turn fastened to electrical conducting pins, such as glass sealed crystal base pins. Presently available crystal devices suffer from a number of substantial disadvantages due to improper crystal blank location in the mounting slots of the supports resulting in a lack of consistent shock performance. Another disadvantage suffered by present crystal devices is inconsistent electrical performance due again to improper crystal blank location in the mounting slots of the supports. The mounting slots may be generally too large or inconsistent in size, and the conductive adhesive can leak through the spaces formed between the crystal blank and the slot. Both of the performance disadvantages of the presently available crystal devices translate directly into higher manufacturing costs as a result of lower production yields of intact and properly functioning crystal devices. Both of the disadvantages also result in decreased customer satisfaction and increased warranty costs for products utilizing the presently available crystal devices. Another disadvantage of prior art crystal devices is the high cost associated with fastening the crystal supports to the electrical connecting pins. This step is highly labor intensive and therefore costly. If great care is not exercised in the fastening process, the problems associated with mounting the crystal blank into the slots of the supports may be compounded.
There continues to be a need for a crystal device that is reliable, less susceptible to shock, especially during manufacture, and inexpensive to produce. Various crystal mounting systems have been proposed to obtain the results required. One such crystal mounting system shows that crystal supports may be independently formed and connected to the electrical connecting pins. This approach, as with other prior art approaches, relies on properly aligning the supports to the electrical connecting pins. Once aligned, the support which incorporates a long slot slightly wider than the thickness of the crystal blank thickness, and a prong having a slit slightly wider than the thickness of the crystal blank and located at the upper end of each support are used in an effort to maintain the alignment of the crystal to the base. Neither this approach nor other prior art approaches have addressed the issues of properly aligning the crystal blank to the base while simplifying the connection of the crystal support to the electrical connecting pins.